Jeong Myeong-hyeon

Du-su is a mischievous high school student known for causing trouble at school. After one of his pranks leads to a fellow student being ostracized, he publicly apologizes and tries to make amends. Through a series of disciplinary punishments and unexpected responsibilities, he gradually becomes more aware of the impact of his actions and begins helping those around him, including a lonely elderly man and a struggling classmate.

Tae-young is a former fighter who now runs a relatively legitimate disco club business. He has a best friend named Joon-suk who runs a bakery with In-hye and is always ready to help Tae-young. When Tae-young refuses to let drug lord Ma Gun-soo use his disco club as a place of business, Gun-soo injects him with drugs and sets him up to the police. Tae-young serves time for a crime he did not commit. After his release, Tae-young attacks Gun-soo's son Tae-ho. Gun-soo retaliates by attacking Joon-suk and In-hye. He tortures and kills Joon-suk. Having lost everything to Gun-soo and his men, Tae-young plans one final battle. He alerts the police to come at a specified moment and prepares for a fight to the finish.